'\" et
.TH UUDECODE "1P" 2017 "IEEE/The Open Group" "POSIX Programmer's Manual"
.\"
.SH PROLOG
This manual page is part of the POSIX Programmer's Manual.
The Linux implementation of this interface may differ (consult
the corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
.\"
.SH NAME
uudecode
\(em decode a binary file
.SH SYNOPSIS
.LP
.nf
uudecode \fB[\fR-o \fIoutfile\fB] [\fIfile\fB]\fR
.fi
.SH DESCRIPTION
The
.IR uudecode
utility shall read a file, or standard input if no file is specified,
that includes data created by the
.IR uuencode
utility. The
.IR uudecode
utility shall scan the input file, searching for data compatible with
one of the formats specified in
.IR uuencode ,
and attempt to create or overwrite the file described by the data (or
overridden by the
.BR \-o
option). The pathname shall be contained in the data or specified by
the
.BR \-o
option. The file access permission bits and contents for the file to be
produced shall be contained in that data. The mode bits of the created
file (other than standard output) shall be set from the file access
permission bits contained in the data; that is, other attributes of the
mode, including the file mode creation mask (see
.IR umask ),
shall not affect the file being produced. If either of the
.IR op
characters
.BR '\(pl' 
and
.BR '\-' 
(see
.IR chmod )
are specified in symbolic mode, the initial mode on which those
operations are based is unspecified.
.P
If the pathname of the file resolves to an existing file and the
user does not have write permission on that file,
.IR uudecode
shall terminate with an error. If the pathname of the file resolves to
an existing file and the user has write permission on that file, the
existing file shall be overwritten and, if possible, the mode bits of
the file (other than standard output) shall be set as described above;
if the mode bits cannot be set,
.IR uudecode
shall not treat this as an error.
.P
If the input data was produced by
.IR uuencode
on a system with a different number of bits per byte than on the target
system, the results of
.IR uudecode
are unspecified.
.SH OPTIONS
The
.IR uudecode
utility shall conform to the Base Definitions volume of POSIX.1\(hy2017,
.IR "Section 12.2" ", " "Utility Syntax Guidelines".
.P
The following option shall be supported by the implementation:
.IP "\fB\-o\ \fIoutfile\fR" 10
A pathname of a file that shall be used instead of any pathname
contained in the input data. Specifying an
.IR outfile
option-argument of
.BR /dev/stdout
shall indicate standard output.
.SH OPERANDS
The following operand shall be supported:
.IP "\fIfile\fR" 10
The pathname of a file containing the output of
.IR uuencode .
.SH STDIN
See the INPUT FILES section.
.SH "INPUT FILES"
The input files shall be files containing the output of
.IR uuencode .
.SH "ENVIRONMENT VARIABLES"
The following environment variables shall affect the execution of
.IR uudecode :
.IP "\fILANG\fP" 10
Provide a default value for the internationalization variables that are
unset or null. (See the Base Definitions volume of POSIX.1\(hy2017,
.IR "Section 8.2" ", " "Internationalization Variables"
for the precedence of internationalization variables used to determine
the values of locale categories.)
.IP "\fILC_ALL\fP" 10
If set to a non-empty string value, override the values of all the
other internationalization variables.
.IP "\fILC_CTYPE\fP" 10
Determine the locale for the interpretation of sequences of bytes of
text data as characters (for example, single-byte as opposed to
multi-byte characters in arguments and input files).
.IP "\fILC_MESSAGES\fP" 10
.br
Determine the locale that should be used to affect the format and
contents of diagnostic messages written to standard error.
.IP "\fINLSPATH\fP" 10
Determine the location of message catalogs for the processing of
.IR LC_MESSAGES .
.SH "ASYNCHRONOUS EVENTS"
Default.
.SH STDOUT
If the file data header encoded by
.IR uuencode
is
.BR \-
or
.BR /dev/stdout ,
or the
.BR \-o
.BR /dev/stdout
option overrides the file data, the standard output shall be in the
same format as the file originally encoded by
.IR uuencode .
Otherwise, the standard output shall not be used.
.SH STDERR
The standard error shall be used only for diagnostic messages.
.SH "OUTPUT FILES"
The output file shall be in the same format as the file originally
encoded by
.IR uuencode .
.SH "EXTENDED DESCRIPTION"
None.
.SH "EXIT STATUS"
The following exit values shall be returned:
.IP "\00" 6
Successful completion.
.IP >0 6
An error occurred.
.SH "CONSEQUENCES OF ERRORS"
Default.
.LP
.IR "The following sections are informative."
.SH "APPLICATION USAGE"
The user who is invoking
.IR uudecode
must have write permission on any file being created.
.P
The output of
.IR uuencode
is essentially an encoded bit stream that is not cognizant of byte
boundaries. It is possible that a 9-bit byte target machine can
process input from an 8-bit source, if it is aware of the requirement,
but the reverse is unlikely to be satisfying. Of course, the only data
that is meaningful for such a transfer between architectures is
generally character data.
.SH EXAMPLES
None.
.SH RATIONALE
Input files are not necessarily text files, as stated by an early
proposal. Although the
.IR uuencode
output is a text file, that output could have been wrapped within
another file or mail message that is not a text file.
.P
The
.BR \-o
option is not historical practice, but was added at the request of WG15
so that the user could override the target pathname without having to
edit the input data itself.
.P
In early drafts, the [\c
.BR \-o
.IR outfile ]
option-argument allowed the use of
.BR \-
to mean standard output. The symbol
.BR \-
has only been used previously in POSIX.1\(hy2008 as a standard input indicator.
The standard developers did not wish to overload the meaning of
.BR \-
in this manner. The
.BR /dev/stdout
concept exists on most modern systems. The
.BR /dev/stdout
syntax does not refer to a new special file. It is just a magic cookie
to specify standard output.
.SH "FUTURE DIRECTIONS"
None.
.SH "SEE ALSO"
.IR "\fIchmod\fR\^",
.IR "\fIumask\fR\^",
.IR "\fIuuencode\fR\^"
.P
The Base Definitions volume of POSIX.1\(hy2017,
.IR "Chapter 8" ", " "Environment Variables",
.IR "Section 12.2" ", " "Utility Syntax Guidelines"
.\"
.SH COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1-2017, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, 2018 Edition,
Copyright (C) 2018 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group.
In the event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .
.PP
Any typographical or formatting errors that appear
in this page are most likely
to have been introduced during the conversion of the source files to
man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
